- ID:
- ivo://CDS.VizieR/J/A+AS/86/209
- Title:
- UBVRI photometry in cluster Tr 18
- Short Name:
- J/A+AS/86/209
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- UBVRI photoelectric photometry was obtained in the field of the open cluster Tr 18. From the analysis of the data we confirm that several distant OB stars were wrongly assumed as cluster members in previous investigations. The true distance modulus is 10.95, equivalent to a distance of 1550pc with the adopted age of (9.0+/-1.0)x10^7^yr. The GH Car Cepheid variable is very much probably a cluster member in view of its spatial position and the average absolute magnitude. However, some arguments are given to suggest that the reality of this cluster is still an open question. The observations in the Cousins system were carried out during 9 nights in April 1989 at Cerro Tololo Interamerican Observatory, with a single channel photometer attaéched to the 60cm Lowell telescope. The positions and identifications with large astrometric surveys was achieved by B. Skiff (Lowell Obs.) in 2010.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/485/3042
- Title:
- UBVRI photometry in 48 globular clusters
- Short Name:
- J/MNRAS/485/3042
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present wide-field, ground-based Johnson-Cousins UBVRI photometry for 48 Galactic globular clusters based on almost 90000 public and proprietary images. The photometry is calibrated with the latest transformations obtained in the framework of our secondary standard project, with typical internal and external uncertainties of order a few millimagnitudes. These data provide a bridge between existing small-area, high-precision HST photometry and all sky-catalogues from large surveys like Gaia, SDSS, or LSST. For many clusters, we present the first publicly available photometry in some of the five bands (typically U and R). We illustrate the scientific potential of the photometry with examples of surface density and brightness profiles and of colour-magnitude diagrams, with the following highlights: (i) we study the morphology of NGC 5904, finding a varying ellipticity and position angle as a function of radial distance; (ii) we show $U$-based colour-magnitude diagrams and demonstrate that no cluster in our sample is free from multiple stellar populations, with the possible exception of a few clusters with high and differential reddening or field contamination, for which more sophisticated investigations are required. This is true even for NGC 5694 and Terzan 8, that were previously considered as (mostly) single-population candidates.
- ID:
- ivo://CDS.VizieR/J/A+A/543/A106
- Title:
- UBVRI photometry in NGC6791
- Short Name:
- J/A+A/543/A106
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new reduction of optical photometry for the open cluster NGC6791.
- ID:
- ivo://CDS.VizieR/J/AJ/134/142
- Title:
- UBVRI photometry in NGC 3367
- Short Name:
- J/AJ/134/142
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report new detailed surface U, B, V, R, and I photometry of 81 stellar structures in the disk of the barred galaxy NGC 3367. The images show many different structures, indicating that star formation is going on in most parts of the disk. NGC 3367 is known to have a very high concentration of molecular gas distribution in the central regions of the galaxy and bipolar synchrotron emission from the nucleus, with two lobes (at 6kpc) forming a triple structure similar to a radio galaxy. We have determined the U, B, V, R, and I magnitudes and U-B, B-V, U-V, and V-I colors for the central region (nucleus), a region which includes supernova 2003 AA, and 79 star associations throughout NGC 3367.
- ID:
- ivo://CDS.VizieR/J/A+A/493/79
- Title:
- UBVRI photometry in Pismis 11 and Alicante 5
- Short Name:
- J/A+A/493/79
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The very luminous blue supergiant HD 80077 has been claimed to be a member of the young open cluster Pismis 11, and hence a hypergiant. Membership of the cluster would mean that it is one of the brightest stars in the Galaxy, and one of the few evolved very massive stars whose distance can be accurately determined. We carry out a comprehensive study of the open cluster Pismis 11, which allows us to derive with accuracy its distance and reddening. We obtained UBVRI photometry of the cluster field and low-resolution spectroscopy of a number of putative members. We derive spectral types from the spectra and determine that the reddening in this direction is standard. We then carry out a careful photometric analysis that allows us to determine individual reddening values, deriving unreddened parameters that are used for the main sequence fit.
- ID:
- ivo://CDS.VizieR/J/AJ/116/2341
- Title:
- UBVRI photometry in Sextans A
- Short Name:
- J/AJ/116/2341
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the relationship between the spatial distributions of stellar populations and of neutral and ionized gas in the Local Group dwarf irregular galaxy Sextans A. We have resolved various populations of stars via deep UBV(RI)_C imaging over an area with diameter 5.3 arcmin. We arrive at 2525 stars detected in V and at least one other band. We provide here the magnitudes, colors, and absolute positions for the stars.
- ID:
- ivo://CDS.VizieR/J/A+AS/115/41
- Title:
- UBV(RI) photometry of cool stars
- Short Name:
- J/A+AS/115/41
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present high-precision UBV(RI)_c_ photometry for a sample of active stars detected serendipitously by the EXOSAT satellite. Fourteen objects, out of 47 likely optical counterparts, turned out to be clearly variable, with periods in the range 1-8 days, including a newly discovered eclipsing binary. For most of them the optical variability is consistent with the presence of photospheric cool spots. We have used our multicolour photometry to estimate spectral classifications and distances. The derived distances indicate that some of the observed stars are previously unidentified nearby (d<=25pc) M dwarfs. When combined with the results of high resolution spectroscopy, our photometric observations allow us to investigate the stellar content of the selected X-ray sample. Young stars and RS CVn-type binaries appear to constitute a large fraction of the selected sample. For a description of the UBV and (RI)c photometric systems, see e.g. <http://obswww.unige.ch/gcpd/ph01.html> and <http://obswww.unige.ch/gcpd/ph54.html>.
- ID:
- ivo://CDS.VizieR/J/A+AS/120/127
- Title:
- UBVRI photometry of 7 dwarfs in Alpha Per
- Short Name:
- J/A+AS/120/127
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The UBVRI light curves of 7 late-type dwarfs amongst the fastest rotators of the Alpha Per cluster (vsini>=140km/s) are presented. The shape of the light curves suggests that the photometric variations are most often dominated by a single group of cool spots located at intermediate or high latitude on the stellar surface. Assuming that starspots are good tracers of the stellar magnetic field, the smooth light curves indicate the existence of a large scale, slowly varying magnetic structure at the surface of these ultrafast rotators. For a description of the UBVRI photometric system, see e.g. <GCPD/08>
- ID:
- ivo://CDS.VizieR/J/A+AS/138/87
- Title:
- UBVRI photometry of EUV stellar sources
- Short Name:
- J/A+AS/138/87
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of high-precision UBV(RI)_c_ photometric observations and of spectroscopic radial velocity measurements obtained at the European Southern Observatory for a sample of 51 cool stars detected in the EUV by the ROSAT Wide Field Camera (WFC). Using also recent results from HIPPARCOS, we infer spectral types and investigate the single or binary nature of the sample stars. Optical variability, with periods in the 0.4-13 day range, has been detected for the first time in 15 of these stars.
- ID:
- ivo://CDS.VizieR/II/277
- Title:
- UBVRI photometry of faint field stars
- Short Name:
- II/277
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This file, originally prepared for the needs of the Lowell Observatory Near-Earth Object Search (LONEOS), contains a rough working collection of Johnson-Cousins UBVRI photometry assembled mainly from the published literature or from publicly available datasets. The V-R and V-I colors are all on the Cousins system. Most of the stars are fainter than V=10.0; the median magnitude is V=13.9, and significant numbers of stars are listed below 20mag. Besides several large surveys, several hundred small sequences in the regions of variable stars, star clusters, galaxies hosting supernovae, quasars, etc were built by determining coordinates for the sequence stars using the published finder charts. At minimum the data include V magnitudes and at least one ordinary photometric color, most commonly B-V. The data were collected for use in determining approximate photometric zero-points in wide-field imaging, with external accuracy of 0.05 mag or better. Though each dataset was vetted for consistency in magnitude and colors, neither high accuracy nor high precision is guaranteed. Obvious variable stars were omitted, but some unknown variables are inevitably included. In any given field, it is advisable use all the available stars for calibration rather than a single comparison. Several large datasets are included. The Guide Star Photometric Catalogue (GSPC, Lasker et al 1988, Cat. II/143) provides BV sequences near the centers of all the Schmidt sky survey plates. At high latitudes in the southern sky, additional data on the 5-degree Schmidt grid were obtained by Platais et al (1998, Cat. I/277) that extend the GSPC sequences to V=~16. More southern fields were observed by Demers et al (1993A&AS...99..437D and 1993A&AS...99..461D); coordinates for these stars have been determined for the first time. Nearly a thousand high-quality sequences in the northern sky have been observed by Henden, partly published in relation to work on cataclysmic variables (e.g. Cat. J/PASP/107/324) and symbiotic stars (e.g. Cat. J/A+A/143/343). Additional Henden sequences have been adopted from the files cited below at the AAVSO ftp site. These large sequences were trimmed to include only a few stars per magnitude interval, and also to omit crowded stars (no significant companions closer than 15" radius). The star coordinates are mainly from early versions of the GSC or USNO series. As such they are given to 1" precision, and in some cases small systematic errors and (now) proper motion mean their accuracy is in the 1" to 5" range. Thus for automated linkage to CCD frames, some modest search radius should be adopted to match with the catalogue. Because the file was originally intended for private use, bibliographic references were not included except in a very few instances. Usually it is straightforward to recover the source paper by inspection of the SIMBAD bibliography for specific objects. Problematic cases can be directed to the compiler (Brian Skiff).
